Ok...not zooxanthaelle, but definitely an indication of stress and possible loss.
I'm with tabwyo, and I sort of figure everyone has tested all parameters and everything is good.
I glanced at some of the pics on your other thread, but they are a little fuzzy so It's hard to say if they were stressed or not. Do you have any good clear shots of the stuff in question?
EDIT
Went back and looked at the pics again....The shrooms in the pics look fine, BUT the smaller tank for your "
quarantine tank" shouldn't have substrate and rocks. It's defeating the purpose of quantining. I'm not really the best to be giving advice on quarantining since I'm notorious for just acclimating and letting them go...but most QT tanks are bare bottomed and only have PVC pieces or pieces of clay pots in them. Do some searching on proper QT techniques....Like I said, I'm a slacker about it but one day that will come to haunt me I know...